Waveguide ferrite circulator having conductive side of dielectric disc in contact with ferrite

ABSTRACT

A high speed microwave device comprises a dielectric waveguide body with conductive interior surfaces, upper and lower triangular transition plates, upper and lower pole pieces extending through the top and bottom walls of the waveguide and partway through the upper and lower transition plates respectively, upper and lower thin dielectric discs within the upper and lower transition plates and in contact with the upper and lower pole pieces respectively, each of the discs having a conductive surface opposite the surface which is in contact with the pole piece, and upper and lower ferrite elements disposed between the transition elements, each including a terminal face in planar abutment with the upper and lower conductive surfaces respectively. The circulator further may include an electromagnet providing rapidly changeable magnetic fields to operate at high switching speeds with excellent wave transmission characteristics but is readily manufactured and assembled.

United States Patent Cotter [451 May 9, 1972 SILVER PLATlllG 47 Primary Examiner-Paul L. Gensler Attorney-Fraser and Bogucki [57] ABSTRACT A high speed microwave device comprises a dielectric waveguide body with conductive interior surfaces, upper and lower triangular transition plates, upper and lower pole pieces extending through the top and bottom walls of the waveguide and partway through the upper and lower transition plates respectively, upper and lower thin dielectric discs within the upper and lower transition plates and in contact with the upper and lower pole pieces respectively, each of the discs having a conductive surface opposite the surface which is in contact with the pole piece, and upper and lower ferrite elements disposed between the transition elements, each including a terminal face in planar abutment with the upper and lower conductive surfaces respectively. The circulator further may include an electromagnet providing rapidly changeable magnetic fields to operate at high switching speeds with excellent wave transmission characteristics but is readily manufactured and assembled.

20 Claims, 7 Drawing Figures PATENTEDMM 9|972 3,662,291

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JOHN J. CUTTER A TTO RNEYS ATENTEWY 9 i972 SHEET 2 BF 3 Ill/l F n-l2 FlG.-3

A TTORNEYS PATENTEUW 19 2 SHEET 3 BF 3 Q SILVER mum;

54 GOLD PLATIN FIG.6

l NVEN! (JR JOHN J. CUTTER ww z" A TTORNEYS WAVEGUIDE FERRITE CIRCULATOR HAVING CONDUCTIVE SIDE OF DIELECTRIC DISC IN CONTACT WITH FERRITE Applications related to the present application and concur- BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to ferrite microwave devices and particularly to such devices having low power lossesfgood wave transmission characteristics, the capability of high switching speeds and relative ease of fabrication and assembly.

2. History of the Prior Art Numerous ferrite microwave devices are known, including circulators, isolators, attenuators and phase shifters, that may be constructed for rectangular waveguide, coaxial lines, strip transmission lines and other forms of wave transmission devices and systems. At the higher microwave frequencies, such devices become extremely small and-mechanical considerations place practical limitations on some performance characteristics. Compromises resulting from mechanical or electrical design can place other limitations on electrical performance. Thus in rectangular waveguide, for example, demanding tolerances must be observed to maintain tolerable insertion losses and VSWR. It is of course feasible to utilize precision machining of each and every part employed in a complex assembly, but assemblies of this nature are generally too costly to find much practical application.

Problems of achieving good transmission characteristics with an easily manufactured assembly are considerably magnified when other characteristics, such as high switching speeds, are also sought. In switchable microwave devices, such as circulators or digital phase shifters, the magnetization of the ferrite is shifted between two different levels, such as between field strengths of equal amplitude but opposite polarity. In such systems the construction of the waveguide itself has a profound effect on switching speeds, because of the eddy current losses that can occur in the waveguide body. The magnetic path through the ferrite cannot have high reluctance segments, but at the same time the wave transmission surfaces cannot incorporate any substantial discontinuities.

SUMMARY OF THE INVENTION Microwave ferrite devices in accordance with the invention incorporate a dielectric disc element having a conductive surface within the magnetic path and in planar contact with the opposite ends of internal microwave ferrite means in a wave transmission member. The magnetic path that extends through the microwave ferrite means and the dielectric discs may be completed by pole piece elements, which for a rectangular waveguide unit may be positioned within a dielectric body structure having internal plated channels to define the waveguide surfaces.

In a specific example of a microwave circulator capable of high speed switching, the circulator body principally comprises a pair of matching molded elements made up of resin matrices having glass fiber reinforcement, and including waveguide-defining recesses having interior plated surfaces. The top and bottom walls of the body portions in the central region of the circulator incorporate pole piece apertures within which pole piece elements are positioned. In this instance the pole pieces protrude to within the interior of the waveguide section. Top and bottom transition elements may.

also be constructed of plated glass fiber reinforced plastic, and include communicating recesses on the opposite sides thereof, for receiving the internal microwave ferrite elements on one side and the associated pole piece on the other. A pair of thin.

dielectric discs, plated on the interior side relative to the waveguide are interposed between the separate pole pieces and the associated ends of the microwave ferrite element or elements. The discs make good areal contact with both the pole pieces and the microwave ferrite elements. An external electromagnet coupled in magnetic circuit with the pole pieces and the internal microwave ferrite elements therefore operates in an efficient magnetic circuit, inasmuch as there are no high reluctance elements in the magnetic path, and there is good contact between the elements, while at the same time the waveguide body has a minimum of eddy current losses. The transition elements assist in providing broadband characteristics, and in this particular arrangement define a reduced height waveguide section incorporating an intermediate height portionencompassing the microwave ferrite. Features of such arrangements are useful in other contexts and other wave transmission structures, inasmuch as the separate components may be readily manufactured and assembled. When used in a rectangular microwave circulator of the type described, such features have pennitted extremely high switching speeds to be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS A BETTER UNDERSTANDING OF THE INVENTION MAY BE HADFROM A CONSIDERATION OF THE FOL- LOWING DETAILED DESCRIPTION, TAKEN IN CON- JUNCTION WITH TI-IE ACCOMPANYING DRAWINGS, IN WHICH:

FIG. 1 is a perspective view, partially broken away, of a microwave ferrite device in accordance with the invention;

FIG. 2 is a plan view, partially broken away, of the microwave device of FIG. 1;

FIG. 3 is a side view of the microwave device of FIG. 1;

FIG. 4 is an exploded view of an interior portion of the device of FIG. 1;

FIG. 5 is a side sectional view of the microwave device shown in FIG. 1;

FIG. 6 is an enlarged fragmentary view of a portion of the section shown in FIG. 5, and showing further details thereof; and,

FIG. 7 is a plan view of a portion of the fragment of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION In the Figures, microwave ferrite devices in accordance with the invention are exemplified by a switchable circulator for a rectangular waveguide. Circulators, as the term' is now used in the art, are conventionally symmetrical multi-terminal devices-having three terminals, for example, symmetrically arranged about a central axis. As with other microwave ferrite devices it is desirable to achieve a low insertion loss and VSWR, while maintaining optimum microwave and magnetic properties. At the same time such devices must be readily fabricated and with reproducible characteristics. It will be recognized by those skilled in the art that features of devices in accordance with the invention may be utilized in other circulators, other microwave ferrite devices and particularly in other switchable ferrite devices. It will also be recognized by those skilled in the art that devices in accordance with this invention need not be limited to a rectangular configuration and may include other'configurations such as coaxial.

In accordance with the invention, referring now to FIGS. 1-3 particularly, the body of a three port circulator 10 comprises a base portion 12 of a somewhat triangular outline in plan view with flanges 13 (FIG. 1 only) for coupling to associated waveguides or elements (not shown). The top surface (as seen in FIG. 2) of the base portion 12 is coplanar with a reference dividingplane, and includes rectangular channels extending radially from a central vertical axis and each defining the side walls and one (the bottom) broad wall of a rectangular waveguide circulator junction. The side faces of the base portion 12 and the flanges 13 lie normal to the respective longitudinal axes of the three different channels 14, the flanges 13 being secured by screws (not shown) threaded into the circulator body. The top portion 16 of the body of the circulator has a substantially flat bottom surface lying in the reference dividing plane and is secured to the base portion 12. The top portion 16 registers with the top of the base portion 12 along the reference dividing plane and the registering bottom surface completes the definition of the three internal rectangular waveguides by defining the remaining broad wall.

Both the base portion 12 and the top portion 16 are dielectric bodies. in the present example of a specific device, these bodies are of a compound manufactured by Cosmic Plastics and designated by them as K66. The compound is molded to size and shape and machined as necessary on the mating surfaces and comprises a glass fiber reinforced diallyl isophthalate molding compound. The diallyl iso-phthalate is a relatively soft material and the fibers are approximately 0.25

inches or more long and approximately 0.010 to 0.015 inches in diameter. Such fiber reinforcement improves the rigidity of the molded product an'dpermits threaded screws to be used for joinder but does not introduce internal stresses when the body parts are machined. It has been found that long or con tinuous fibers give rise to internal stresses on machining and these must be relieved by tempering processes that themselves give rise to distortions. By providing a stable, machinable and adequately strong structure such body is much superior to other non-metallic waveguide constructions that have been suggested. The use of exterior flanges 13 provides a standard coupling to associated units, some additional protective shielding and better external wearingsurfaces.

The body of the circulator 10 is joined by screws 18 threaded from the top portion 16 into the base portion 12. The three terminal ports 20, 21, 22 of the circulator 10 are to be coupled to associated devices for typical circulator clockwise or counterclockwise action dependent upon the sense of ferrite magnetization. The internal waveguide structure is' rendered conductive by a thin gold plating of 0.0002-00005 inches in thickness. At the side faces only a lip portion 24 at the end of each waveguide channel 14 is gold plated, and in contact with the associated flange 13 (FIG. 1 only).

Thus the body of the circulator 10 may be seen to comprise three symmetrically displaced waveguide terminals 20, 21, 22 with an interior central region in which the ferrite element and the associated magnetic elements are to be disposed relative to the central axis. The term central axis hereafter will be intended to refer to the interior axis normal to the broad faces of the waveguides. Although the waveguides are shown in a symmetrical Y configuration, they may alternatively be somewhat asymmetrical, such as a T configuration, or the device may have four or more symmetrical ports. What may be said to be the top and bottom portions of the circulator 10 incorporate notched and recessedportions 26, 27 about the central axis for receiving a magnet in close fitting relation as described below. A pair of circular pole piece apertures 30, 31' are symmetrically disposed about the central axis to provide communication through the top and bottom walls of the circulator 10 between the recessed portions 26, 27 and the interior waveguide portion.

An electromagnet 33 comprising a generally C-shaped core 35 and an encompassing coil 37 is disposed about the body of the circulator 10, with the core tips being registered within the opposite principal recesses 26, 27 respectively. For good magnetic coupling, the opposite tips of the core 35 have surfaces concentric with and normal to the central axis. Bidirectional current driver circuits 39 are coupled to the coil 37 of the electromagnet 33, to provide internal magnetization with a flux of either polarity, and rapid switching between opposite polarities. v

The magnetic ferrite circuit is best seen in FIGS. 4-7 and comprises a series of elements between the opposite faces of the electromagnet core 35, these being symmetrically disposed about the central axis within the internal waveguides. A pair of cylindrical ferrite pole pieces 41, 42 are. separately disposed within the different circular pole piece apertures 30, 31 in the circulator body 10. The pole pieces 41, 42 register within the apertures with a close fit, and have opposite upper and lowerflat faces for intimate areal contact with the associated elements in the magnetic circuit. The interior faces of the pole pieces 41, 42, with respect to the center of the waveguide structure, abut a pair of thin dielectric discs 44, 45, being bonded thereto by a thin layer of high strength bonding material. An exemplary material, used in this example, is sold by H. B. Fuller & Co. under the trademark "Resiweld 7004". The dielectric discs 44, 45 are approximately 0.010 inches thick of AL-300 material, and include a silver plated layer 47,

48 on the side facing the interior of the waveguide. The discs 44, 45 are circular and conform in plan outline to the ferrite pole pieces 41, 42. It will be noted that the pole pieces 41, 42 protrude internally through the pole piece apertures 30, 31 a selected distance into the interior of the waveguide. The silver plated surfaces of the dielectric discs 44, 45 therefore establish between them a central intermediate height waveguide section, as is described in more detail hereafter; The internally protruding portions of the pole pieces 41, 42 and the discs 44, 45 lie within matching recesses in different ones of a pair of triangular stepped transition sections 50, 51, each difierent apex of the transition sections 50, 51 being pointed along a different waveguide arm in the circulator 10. The transition sections 50, 51 advantageously comprise conductively plated fiber reinforced plastic and molded bodies that correspond to the body portions 12, 16. The different sections 50, 51v are separately affixed to the top and bottom waveguide walls respectively. Taking the top section 50 as a specific example, a first step portion 53 of greatest area is disposed directly against the waveguide wall, with a second step portion 54 of similar configuration but having lesser area disposed within it. The height of the steps 53, 54 relative to the waveguide height are selected in accordance withknown impedance matching and waveguide transition characteristics to provide a transformation between the standard height waveguide portion and the ferrite filled waveguide portion.

Again taking the top transition section 50 for reference, a circular recess 56 extending inwardly from the broad wall side of the transition section 50 is sunk to a particular chosen depth within the interior of the section 50, and communicates with a triangular recess 58 that is inset in from the opposite side of the transition section 50. The triangular recess is of a size such that its apexes are on a circumference of the circular recess and lie along the transition element at like radii from the central axis as do the apexes of the transition section 50 itself. The bottom transition section 51 is similarly arranged and the same description applies. The transition sections 50, '51 improve the bandwidth characteristics of the circulator but need not be employed, nor need they be of triangular form. Tuning screws (not shown) may be incorporated, as near the transition section apices for further adjustments.

- A pair of triangular microwave ferrite elements 60, 61 are each disposed within a different triangular recess 58 in the top and bottom transition sections 50, 51 respectively. These microwave ferrite elements 60, 61 are triangular when viewed in plan view and have broad upper and lower faces that lie normal to the central axis. The upper and lower faces of the top and bottom microwave ferrite elements 60, 61 abut the silver plated surfaces 47, 48 of the dielectric discs 44, 45 respectively and are bonded thereto by a mixture of silver epoxy and Resiweld." The microwave ferrite elements 60, 61 are separated by a Teflon dielectric insulator 63 that comprises the central element in this ferrite-magnetic circuit.

Those skilled in the art will recognize a substantial number of instructional and operative advantages in this system. The dielectric body of the circulator 10 is readily molded into a complex shape, but nevertheless-the precision surfaces defining the waveguides, the abutting surfaces of the base portion 12 and the top portion 16 require only simple machining for precise dimensioning. The dielectric body introduces extremely low eddy current loss into the magnetic circuit even under high switching speeds, while the internally plated waveguide surfaces transmit the electromagnetic wave energy with extremely high efficiency.

The magnetic characteristics of the magnet-ferrite circuit, and the transmission of the electromagnetic wave energy of the microwave device provide an advantageous combination of superior properties. Ferrite or soft iron pole pieces such as the elements 41, 42 have been in extensive use in microwave ferrite devices as an insert between an external magnetic device and an internal microwave ferrite component, because the presence of a pole piece provides some wave conduction without introducing a high magnetic reluctance. However, when substantial performance demands are placed on the circulator or other ferrite device, such as extremely high switching speeds, together with low insertion loss and VSWR, the iron pole piece becomes inadequate. Attempts have been made to improve the wave propagation characteristics by plating the interior surface of the pole piece, but this in turn has given rise to substantial different problems. it must be borne in mind that surface irregularity in the magnet core tips, or in the abutting surfaces of the pole pieces or microwave ferrite can have profound effect on electrical and magnetic characteristics even though only extremely small displacements are involved. in addition, such small factors as a degree of permeation of a porous pole piece with a plating material can introduce an undesired and variable amount of resistance into the circuit.

Such problems have been obviated by the present arrangement, comprising a dielectric disc plated on its interior waveguide side and providing the desired areal abutment against both the pole piece and the adjacent microwave ferrite element. No extreme demands in terms of fabrication or machining are placed on any of the elements. The pole piece, disc and microwave ferrite elements are each readily machined and added to the assembly.

lt should particularly be noted that an efficient waveguide structure is readily provided by this arrangement. Transition elements where used may either be of a molded non-metallic body with plating or individual metal elements. The insertion of the ferrite into the recesses in the associated transition sections permits more ferrite material to be included with better matching properties. The effective height of the waveguide in the immediate region of the ferrite is intermediate between the smallest dimension between the transition sections and the nominal waveguide height. Accordingly, the waveguide height directly at the ferrite region may be optimized. The Teflon insulator centrally disposed between the ferrite elements provides dielectric loading and may incorporate a centrally disposed shim or plate element (not shown) for wave suppression if desired. The following are characteristics of a high speed switch circulator built in accordance with the above example and operated at 7.2 to 10.05 GHz:

VSWR 1.20/1 insertion Loss 0.3 db. Isolation 20 db. Switching Time psec.

An alternative arrangement in accordance with the invention may utilize a membrane within the individual transition sections of a thickness comparable to the dielectric disc which is plated on the inner side for providing a waveguide surface. It is found, however, that the membrane is likely to be broken by inexperienced personnel during handling, although it is satisfactorily secure once it is assembled. Other modifications, variations and alternatives will suggest themselves to those skilled in the art, such as plating the microwave ferrite on the side abutting the disc, or using silver, copper or some other conductor for the plating material where gold has been used in the example. The scope of the invention is to be construed as incorporating all modifications and changes within the ap' pended claims.

What is claimed is:

l. A microwave ferrite device comprising:

means defining a waveguide having a selected standardized height;

means including transition means positioned within said waveguide to define a reduced height portion; means including ferrite means defining a microwave ferrite zone within said reduced height portion, the means including 5 ferrite means having a height greater than the reduced height portion so as to extend from regions intermediate the transition means into the transition means; dielectric means positioned on opposite sides of said ferrite means and including thin conductive surfaces in contact with the ferrite means; and means abutting said dielectric means for establishing a magnetic field through said ferrite means. 2. The microwave ferrite device of claim 1 wherein the l 5 dielectric means comprises a pair of elements positioned on opposite sides of the ferrite means.

3. A microwave ferrite device comprising:

waveguide means having a selected standardized wave transmission conduit, said waveguide means comprising a non-metallic body and interior metallic surface plating, and having apertures in said body about a selected axis substantially normal thereto;

ferrite means disposed within the wave transmission conduit along the selected axis;

dielectric means positioned within the apertures and in abutment with said ferrite means, said dielectric means having thin conductive surfaces contacting said ferrite means; and

means abutting said dielectric means for establishing a magnetic field through said ferrite means.

4. The invention as set forth in claim 3 above, wherein said means abutting said dielectric means includes pole piece means at least partially disposed within the apertures of said waveguide means.

5. The invention as set forth'in claim 4 above, including transition means disposed in said wave transmission conduit about the axis and providing a reduced height conduit about said ferrite means.

6. A microwave ferrite device comprising: a dielectric body 40 having an interior channel defining a waveguide, said waveguide including a reduced height waveguide portion and apertures in communication with said reduced height portion;

a conductive surface disposed on the interior channel; a pair of pole pieces disposed in said apertures;

ferrite means disposed between said pole pieces; and

a pair of thin dielectric elements, each interposed between said ferrite means and a different one of said pole pieces, each of said dielectric elements having a planar conductive surface on the side abutting said ferrite means making intimate planar contact with said ferrite means.

7. The microwave ferrite device of claim 6 wherein the conductive surface disposed on the interior channel is gold plating and the planar conductive surfaces on the dielectric elements is silver plating.

8. The microwave ferrite device of claim 7 wherein said gold plating and silver plating have a thickness no less than about 0.0002 inch and no greater than about 0.0005 inch.

9. A high speed microwave circulator comprising:

a waveguide section having three rectangular waveguide paths, the longitudinal axes of which radiate from an orthogonal central axis at substantially equal angles from each other, said section including top and bottom portions, each having a circular aperture therein concentric with said central axis;

upper and lower pole pieces extending through the top and bottom apertures respectively;

upper and lower thin dielectric discs abutting the upper and lower pole pieces respectively, each of said discs including a thin conducting surface opposite the abutting surface;

upper and lower triangular transition plates disposed within the waveguide section with a broad base surface adjacent the top and bottom respectively and an interior step section, each broad base surface having a circular recess therein receiving a different pole piece and disc with the thin conducting surface being bonded to the transition plate, and each interior step section having a triangular recess therein communicating with the circular recess; upper and lower triangular ferrite elements having a terminal end disposed within the triangular recess of an upper and lower transition plate respectively abutting and bonded to the thin conductive surface therein; and

a dielectric element disposed between said upper and lower ferrite elements.

10. The microwave device of claim 9 further comprising means for inducing a rapidly changeable magnetic field between said upper and lower pole pieces.

1 l. A high switching rate microwave circulator comprising:

a dielectric waveguide body with interior waveguide defining surfaces of conductive material and including top and bottom portions, each having an aperture therein about a central axis; upper and lower transition means disposed within the waveguide section about said central axis, said means each including a central aperture about said central axis;

upper and lower pole piece elements, each extending through a different one of the waveguide body apertures and into the central aperture of said transition means;

upper and lower dielectric discs having one broad surface abutting the upper and lower pole piece elements respectively and a thin conductive surface opposite the abutting surface; and

upper and lower ferrite elements partly within the apertures in the upper and lower transition means and abutting the upper and lower conductive surfaces of said discs respectively.

12. The circulator of claim 11 wherein said discs are approximately 0.010 inches in thickness and the thin conductive surfaces are approximately 0.0002 to 0.0005 inches in thickness, and including in addition electromagnet means coupled to said upper and lower pole pieces, and means for switching said electromagnet means rapidly between two different magnetization levels.

13. The invention as set forth in claim 12, wherein said pole piece elements comprise ferrite material and wherein in addition a dielectric element is disposed between said ferrite elements.

14. The circulator of claim 12 wherein said circulator comprises a three port device, wherein said transition means comprises a pair of double step triangular elements, and wherein said ferrite elements are triangular in shape.

15. The invention as set forth in claim 14, wherein said transition elements define an interior reduced height section and the conductive surfaces of said discs define a section of intermediate height between the waveguide surfaces and said reduced height section, and wherein said transition elements and said waveguide body are of fiber reinforced plastic.

16. The invention as set forth in claim 15, wherein said fiber reinforced plastic comprises relatively short length glass fibers in a diallyl phthalate matrix.

17. The invention as set forth in claim 16 above, wherein said diallyl phthalate is diallyl iso-phthalate and wherein said glass fibers are about one-fourth inch in length and about 0.010 to 0.015 inches in diameter.

18. A microwave ferrite device comprising:

wave transmission means comprising a non-metallic, hollow body having a thin interior metallic coating defining wave conducting surfaces and at least one aperture therein;

dielectric means disposed within the aperture and having a relatively flat, conductive surface; v ferrite means disposed within the hollow interior of the body and extending into the aperture and into contact with the conductive surface of the dielectric means; and means for magnetizing the ferrite means in a selected direction. 19. The microwave ferrite device of claim 18, wherein the at least one aperture is enerally circular in shape, the dielectric means comprises a least one disc of dielectric material having one side thereof coated with a conductive material to define the conductive surface and mounted generally concentrically within the aperture, and the ferrite means comprises at least one disc of ferrite material having one side thereof disposed in contact with the conductive surface of the dielectric disc.

20. The microwave ferrite device of claim 18, wherein the hollow body has a pair of apertures therein on opposite sides of the hollow interior, the dielectric means comprises a pair of discs of dielectric material, each having one side thereof coated with a conductive material to define the conductive surface and disposed within a different one of the apertures, and the ferrite means comprises a pair of discs of ferrite material, each of which has one side thereof disposed in contact with the conductive surface of a different one of the dielectric discs. 

1. A microwave ferrite device comprising: means defining a waveguide having a selected standardized height; means including transition means positioned within said waveguide to define a reduced height portion; means including ferrite means defining a microwave ferrite zone within said reduced height portion, the means including ferrite means having a height greater than the reduced height portion so as to extend from regions intermediate the transition means into the transition means; dielectric means positioned on opposite sides of said ferrite means and including thin conductive surfaces in contact with the ferrite means; and means abutting said dielectric means for establishing a magnetic field through said ferrite means.
 2. The microwave ferrite device of claim 1 wherein the dielectric means comprises a pair of elements positioned on opposite sides of the ferrite means.
 3. A microwave ferrite device comprising: waveguide means having a selected standardized wave transmission conduit, said waveguide means comprising a non-metallic body and interior metallic surface plating, and having apertures in said body about a selected axis substantially normal thereto; ferrite means disposed within the wave transmission conduit along the selected axis; dielectric means positioned within the apertures and in abutment with said ferrite means, said dielectric means having thin conductive surfaces contacting said ferrite means; and means abutting said dielectric means for establishing a magnetic field through said ferrite means.
 4. The invention as set forth in claim 3 above, wherein said means abutting said dielectric means includes pole piece means at least partially disposed within the apertures of said waveguide means.
 5. The invention as set forth in claim 4 above, including transition means disposed in said wave transmission conduit about tHe axis and providing a reduced height conduit about said ferrite means.
 6. A microwave ferrite device comprising: a dielectric body having an interior channel defining a waveguide, said waveguide including a reduced height waveguide portion and apertures in communication with said reduced height portion; a conductive surface disposed on the interior channel; a pair of pole pieces disposed in said apertures; ferrite means disposed between said pole pieces; and a pair of thin dielectric elements, each interposed between said ferrite means and a different one of said pole pieces, each of said dielectric elements having a planar conductive surface on the side abutting said ferrite means making intimate planar contact with said ferrite means.
 7. The microwave ferrite device of claim 6 wherein the conductive surface disposed on the interior channel is gold plating and the planar conductive surfaces on the dielectric elements is silver plating.
 8. The microwave ferrite device of claim 7 wherein said gold plating and silver plating have a thickness no less than about 0.0002 inch and no greater than about 0.0005 inch.
 9. A high speed microwave circulator comprising: a waveguide section having three rectangular waveguide paths, the longitudinal axes of which radiate from an orthogonal central axis at substantially equal angles from each other, said section including top and bottom portions, each having a circular aperture therein concentric with said central axis; upper and lower pole pieces extending through the top and bottom apertures respectively; upper and lower thin dielectric discs abutting the upper and lower pole pieces respectively, each of said discs including a thin conducting surface opposite the abutting surface; upper and lower triangular transition plates disposed within the waveguide section with a broad base surface adjacent the top and bottom respectively and an interior step section, each broad base surface having a circular recess therein receiving a different pole piece and disc with the thin conducting surface being bonded to the transition plate, and each interior step section having a triangular recess therein communicating with the circular recess; upper and lower triangular ferrite elements having a terminal end disposed within the triangular recess of an upper and lower transition plate respectively abutting and bonded to the thin conductive surface therein; and a dielectric element disposed between said upper and lower ferrite elements.
 10. The microwave device of claim 9 further comprising means for inducing a rapidly changeable magnetic field between said upper and lower pole pieces.
 11. A high switching rate microwave circulator comprising: a dielectric waveguide body with interior waveguide defining surfaces of conductive material and including top and bottom portions, each having an aperture therein about a central axis; upper and lower transition means disposed within the waveguide section about said central axis, said means each including a central aperture about said central axis; upper and lower pole piece elements, each extending through a different one of the waveguide body apertures and into the central aperture of said transition means; upper and lower dielectric discs having one broad surface abutting the upper and lower pole piece elements respectively and a thin conductive surface opposite the abutting surface; and upper and lower ferrite elements partly within the apertures in the upper and lower transition means and abutting the upper and lower conductive surfaces of said discs respectively.
 12. The circulator of claim 11 wherein said discs are approximately 0.010 inches in thickness and the thin conductive surfaces are approximately 0.0002 to 0.0005 inches in thickness, and including in addition electromagnet means coupled to said upper and lower pole pieces, and means for switching said electromagnet means rapiDly between two different magnetization levels.
 13. The invention as set forth in claim 12, wherein said pole piece elements comprise ferrite material and wherein in addition a dielectric element is disposed between said ferrite elements.
 14. The circulator of claim 12 wherein said circulator comprises a three port device, wherein said transition means comprises a pair of double step triangular elements, and wherein said ferrite elements are triangular in shape.
 15. The invention as set forth in claim 14, wherein said transition elements define an interior reduced height section and the conductive surfaces of said discs define a section of intermediate height between the waveguide surfaces and said reduced height section, and wherein said transition elements and said waveguide body are of fiber reinforced plastic.
 16. The invention as set forth in claim 15, wherein said fiber reinforced plastic comprises relatively short length glass fibers in a diallyl phthalate matrix.
 17. The invention as set forth in claim 16 above, wherein said diallyl phthalate is diallyl iso-phthalate and wherein said glass fibers are about one-fourth inch in length and about 0.010 to 0.015 inches in diameter.
 18. A microwave ferrite device comprising: wave transmission means comprising a non-metallic, hollow body having a thin interior metallic coating defining wave conducting surfaces and at least one aperture therein; dielectric means disposed within the aperture and having a relatively flat, conductive surface; ferrite means disposed within the hollow interior of the body and extending into the aperture and into contact with the conductive surface of the dielectric means; and means for magnetizing the ferrite means in a selected direction.
 19. The microwave ferrite device of claim 18, wherein the at least one aperture is generally circular in shape, the dielectric means comprises at least one disc of dielectric material having one side thereof coated with a conductive material to define the conductive surface and mounted generally concentrically within the aperture, and the ferrite means comprises at least one disc of ferrite material having one side thereof disposed in contact with the conductive surface of the dielectric disc.
 20. The microwave ferrite device of claim 18, wherein the hollow body has a pair of apertures therein on opposite sides of the hollow interior, the dielectric means comprises a pair of discs of dielectric material, each having one side thereof coated with a conductive material to define the conductive surface and disposed within a different one of the apertures, and the ferrite means comprises a pair of discs of ferrite material, each of which has one side thereof disposed in contact with the conductive surface of a different one of the dielectric discs. 